Window glass installed in present day motor vehicles typically incorporates a blacked out band extending around the peripheral edge portion of the glass to which adhesives are applied to secure the window glass to the vehicle. In order to prepare the glass for the adhesive, it is necessary to apply a dear coat to etch and clean the glass. Next, an initial primer coating is applied to the window glass. After the primer coating is allowed to dry, an adhesive is applied to the outer circumferential portion of the glass which is then installed in the vehicle. In some vehicle designs, the blacked out band is eliminated and the adhesive is applied directly to the outer circumferential portion of the glass itself.
The process for applying the various coatings and in particular the primer to the glass utilizes a supply of the specific coating that is dispensed through a nozzle to the central core of a brush. The brush is typically attached to the nozzle using a threaded connection or some other type of connecting system known in the art. The nozzle and brush assembly are moved around the outer circumference of the glass by an articulated robot arm while the coating is being dispensed into the brush by the nozzle. In the alternative, the glass can be moved with respect to the brush rather than the brush with respect to the glass. Once the application of the coating has been completed, the glass is assembled to the motor vehicle.
These prior art nozzle/brush systems have performed satisfactory but there are certain areas which can be improved upon. One area which provides some problems for the manufacturer is the durability of the brush which is attached to the nozzle. During the application of the coating, the bristles of the brush sweep against the glass to provide a consistent application of the coating. As the bristles sweep across the glass, they begin to wear down and eventually have to be replaced. In order to apply a proper amount and a proper distribution of the coating, the free length of the bristles needs to be maintained within a specified tolerance. If the free end of the bristles are too long, the width of the coating will become excessive. If the free end of the bristles are too short, the width of the coating will be too small. Typically, a brush will last from one to two hours of production after which the free end of the bristles become too short and the machine must be stopped in order to replace the brush on the nozzle. The threaded connection between the brush and the nozzle facilitate this changeover. The need to stop the machine in order to replace the brush produces downtime which adversely effects the productivity of the assembly process. Thus, it would be advantageous to develop a system which minimizes or eliminates the downtime associated with the replacement of the brushes for this coating application system.
The present invention provides the art with a system that essentially eliminates the downtime associated with replacement of the brushes for a coating application system. The brush replacement system of the present invention provides a two stage system for renewing the brush which is attached to the nozzle. The first stage of the system utilizes a brush which has an extended length of bristles. A plastic sleeve surrounds the bristles and the housing supporting the bristles. After a specified period has elapsed, the assembly machine cycles to a station where a portion of the plastic sleeve adjacent the bristles is trimmed away to expose an additional portion of the extended length of bristle. This process continues until all of the plastic sleeve surrounding the bristles has been removed. Once all of the plastic sleeve has been removed, the brush replacement system enters the second stage. In the second stage, the assembly machine cycles to automatically discard the used brush and automatically obtain a new brush from a magazine or supply of new brushes disposed adjacent to the machine. The application of the coating continues with the new brush and the process begins again. The machine utilizes a quick connect system between the nozzle and the brush to facilitate the automatic replacement of the brush. Typically the trimming of the plastic sleeve and/or the replacement of the brush can be accomplished during the normal cycle time for the assembly process thus eliminating the brush replacement related down time.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.